Devices for cleaning wiping cylinders in a printing apparatus

ABSTRACT

A device for cleaning a rotatable wiping cylinder of a printing apparatus comprises a receptacle for cleaning fluid adapted to operatively receive a portion of the periphery of the wiping cylinder, and a scraper mounted for movement between a first position in which it engages the periphery of the wiping cylinder and a second position in which it is spaced from the periphery of the wiping cylinder. A plurality of scrapers and a brush are provided downstream of the scraper in the direction of rotation of the wiping cylinder for engaging the periphery of the wiping cylinder.

llnited States Patent Giori [151 3,656,431 1 Apr. 18, 1972 [54] DEVICESFOR CLEANING WIPING CYLINDERS IN A PRINTING APPARATUS [72] Inventor:Gualtiero Giori, Lausanne, Switzerland {73] Assigne'e: De La Rue GioriS.A., Lausanne, Switzerland [22] Filed: May 22, 1970 [21] Appl. No.:39,608

[30] Foreign Application Priority Data May 23, 1969 Switzerland..7900/69 [52] U.S.Cl ..101/425, 101/167, 101/169 [51] Int. Cl. ..B4lf9/16 [58] Field ofSearch ..l0l/155,157,167,169,423-425 [56] ReferencesCited UNITED STATES PATENTS 3,026,796 3/1962 Crawford ..101/1572,987,993 6/1961 Giori ..101/155 Primary Examiner-J. Reed FisherAttorneyRobert E. Burns and Emmanuel .I. Lobato [5 7] ABSTRACT A devicefor cleaning a rotatable wiping cylinder of a printing apparatuscomprises a receptacle for cleaning fluid adapted to operatively receivea portion of the periphery of the wiping cylinder, and a scraper mountedfor movement between a first position in which it engages the peripheryof the wiping cylinder and a second position in which it is spaced fromthe periphery of the wiping cylinder. A plurality of scrapers and abrush are provided downstream of the scraper in the direction ofrotation of the wiping cylinder for engaging the periphery of the wipingcylinder.

8 Claims, 2 Drawing Figures DEVICES FOR CLEANING WIPING CYLINDERS IN APRINTING APPARATUS BACKGROUND OF THE INVENTION The present inventionrelates to printing apparatus, and in particular to devices for cleaningrotatable wiping cylinders of printing apparatus for copper-plateprinting in at least one color.

Printing apparatus is known comprising at least one revolving brushapplied at a predetermined'point to the wiping cylinder within thedamping zone, a scraper placed downstream of the damping zone, in thedirection of the rotation of the wiping cylinder and downstream of thescraper, a system of nozzles, spraying water onto the surface of thewiping cylinder, as well as a supplementary scraper to remove the filmof water from the surface of the wiping cylinder. This known apparatuspermits the use of an aqueous solution which includes an alkalinewashing ingredient, a cleaning agent well known in the trade, with abase of alkaline phosphate and a wetting agent. As a result, theexpensive organic solvent, trichloreythylene which was used in apractically exclusive manner in printing apparatus before the disclosureof this known apparatus, is not now required. With this known apparatus,the revolving brushes, combine with the action of the cleaning liquids,to eliminate the total volume of ink on the wiping cylinder with theresult that the brushes rapidly become clogged up, and wear out so thatthey must often be renewed. In addition, the support, driving therotating brushes employed up to the present time, and the replacement ofthe said brushes leads to a complicated assembly and maintenance of thisdevice.

Another disadvantage with revolving brushes results from the fact thatthe bristles, because of their relatively high speed, break down the inklifted off the wiping cylinder, into small particles thereby creating aconstant, severe turbulence of the cleaning liquid, in such a way thatafter a short working period the cleaning liquid is saturated with smallparticles of ink disposed in constant suspension and agitation. It is,therefore, necessary to replace the cleaning liquid frequently. However,it is thought that the fragmentation of the ink, caused by the turningbrushes, producing fine particles, is better in order to obtain a goodcleaning action, as it then produces a very quick dispersion. It is trueto say, that this problem is not evident when trichlorethylene is usedas, in this case, a rapid physical dispersion of the ink is produced.

Moreover, in the known apparatus, the scraper which takes off thegreater part of the ink on the rim of the wiping cylinder, before thedamping zone, is very strongly pressed against the wiping cylinder andthere is a risk than when the wiping cylinder closes to rotate, that theedge of the scraper will penetrate the cylinder surface, which isusually made of synthetic material, and make the cylinder unusable.

OBJECTS OF THE INVENTION The invention is based on this problem; toremedy the aforementioned drawbacks, inherent with a scraper staticallymounted in front of the damping zone of the wiping cylinder, and toprovide a simple device which is more economical than those of cleaningsystems fitted with rotating brushes,and which at the same time benefitsfrom advantages which are brought about by the use of a first scraper,mounted upstream in the direction of the rotation of the wiping cylinderrelative to cleaning means which scraper mechanically takes off thegreater part of the ink on the periphery of the cylinder. At the sametime a preferred embodiment of the invention minimizes the too finedispersion of the ink volume in the cleaning liquid which can, as aresult, be used for a longer time without being replaced.

According to the present invention, a device for cleaning a rotatablewiping cylinder of a printing apparatus comprises a receptacle forcleaning fluid, and a scraper mounted for move ment between first andsecond positions, the device being so arranged that when operativelycombined with the wiping cylinder, the receptacle receives a portion ofthe wiping cylinder, and the scraper engages the periphery of the wipingcylinder when in its first position and is spaced from the wipingcylinder when in its second position.

The scraper, which may be made from sheet steel, may be placed before orwithin the damping zone of the wiping cylinder. It removes the ink fromthe wiping cylinder in large shavings like swarf, and because of itsposition in, for example, the damping zone, the cleaning fluid in thereceptacle serves as a complementary lubricant and cooling fluid. Whenthe volume of ink so removed remains in one piece, Le, a shaving, itsinks rapidly to the bottom of the receptacle, without substantiallyeffecting the next cleaning process, such that, if brushes are used,these only become dirty very slowly. In addition, there is no need toinstall cleaning devices other than static cleaning means in thereceptacle, which cleaning means are easily detachable and, preferablyinterchangeable.

DESCRIPTION OF DRAWINGS An embodiment of the invention will now bedescribed, by way of example, reference being made to the accompanyingdrawings in which:

FIG. 1 is a partly sectional side elevation of a device for cleaning arotatable wiping cylinder of a printing apparatus; and

FIG. 2 is an enlarged detail of FIG. 1.

DESCRIPTION OF PREFERRED EMBODIMENT:

As shown, a wiping cylinder 1 of a printing apparatus for copper-plateprinting in one or several colours is rotatable about position in asense indicated by arrow F1, and contacts at its periphery the peripheryof a plate cylinder 2 provided with a printing plate. The lower portionof the periphery of wiping cylinder 1 is received in a receptacle 3filled with a known aqueous alkaline cleaning liquid.

Adjacent the two opposed side walls of receptacle 3, facing the sides ofwiping cylinder 1, two elongated, arcuate rails 4 (only one shown) areco-axially positioned with respect to wiping cylinder 1, and mounted onguide means in the form of guide rollers 7. Rollers 7 are rotatablymounted on the opposed side walls to permit the rails 4 to slide alongan arcuate path substantially co-axial with the wiping cylinder 1. Eachrail 4 has attached to its left hand end, as seen in FIG. 1, a rack rail5 having gear teeth which co-operate with the teeth of a pinion 6mounted on an operating shaft 6a.

A plurality of spiral springs 12 to are each attached at one end to arail 4 by means of pins 8 to 11. At its opposite end, each spring 12 to15 is pivotally connected by means of a pin 16 to 19 to an operating arm20 to 23. As shown, the springs are arranged to lay generally in thelengthwise direction of the rail. Each operating arm 20 to 23 isconnected adjacent one end, to a support shaft 27 to arranged parallelto the rotational axis of the wiping cylinder 1. Each support shaft ismounted at each end in a semi-circular groove in a support plate 48, thegroove being open in the direction facing the periphery of the wipingcylinder. The support plates 48 (only one shown) are fixed to theopposed side walls of receptacle 3.

Scraper support members 24 to 26' are mounted on shafts 28 to 30respectively. The scrapers are each made of rubber 33 to 35 mounted on astiffening plate of sheet steel or iron 33a to 35a.

A brush support 31 fitted with a brush 32 is mounted on shaft 27. Thebristle head of brush 32 is detachable, for example, by means of ascrew, and is fitted to support 31 so that the bristle head can bereplaced without dismantling support 31 or the shaft 27.

The scrapers 33 to 35 and brush 32 extend over the full width of theperiphery of wiping cylinder 1 and bear against the periphery at apredetermined pressure. The pressure at which the scrapers 33 to 35 andbrush 32 engage the periphery is adjustable by slidably moving the rails4.

To reduce the pressure of engagement of the scrapers 24 to 26 and brush32 on the periphery, a screw mechanism (not shown) is turned outside thereceptacle 3, rotation of which turns shaft 6a and pinion 6 whichengages the gear teeth of ratchet rails to move rails 4 in acounter-clockwise sense (as seen in FIG. 1). By means of pins 16 to 19,springs 12 to 15, pins 16 to 19, and operating 20 to 23, the supportshafts 27 to 30 are rotated in a counter-clockwise sense taking withthem support members 24 to 26 and 31, so that scrapers 33 to and brush32 are moved away from the periphery of the wiper cylinder 1.

Movement of the shaft 6a in the opposite direction of rotation will havethe reverse effect and scrapers 33 to 35 and brush 32 will move towardsthe periphery of the wiper cylinder.

As operating arms 20 to 23 are connected to rails 4 by springs 12 to 15,these springs exert a tightening down pressure and consequently thescrapers 33 to 35 and brush 32 having a spring and flexible contact withthe wiping cylinder.

As is shown in FIG. 1, scrapers 33 to 35, in their working positions,form different acute angles with the periphery ofthe wiping cylinders 1.

As the wiping cylinder 1 rotates, itfirst comes into contact with ascraper 36, made from sheet steel, the support member 37 of which isconnected to a shaft 38 rotatably mounted in bearings 39. An operatingarm 40 is attached at each end to shaft 38, and each arm 40 is pivotallymounted on pin 40 on a head 42 of a hydraulic piston 43 of a piston andcylinder device 44 mounted for pivotal movement about pivot 45. Twohydraulic devices (only one shown) able to be driven simultaneously, areso arranged for the rotation of shaft 38 on the two sides of thereceptacle. In the working position, piston 43 is raised in such a waythat scraper 36 is pressed against the wiping cylinder 1, at a givenpressure. This scraper 36 is, as shown in FIG. 1, at least practicallytangential to the wiping cylinder and forms an acute angle with theperiphery of the latter. To lift the scraper 36 off the periphery of thewiping cylinder 1 when the cylinder 1 is not working, it is onlynecessary that the piston 43 is retracted or moved to its lowerposition, by means of a conventional electro-hydraulic relay (notshown). Lowering the piston 43 causes shaft 38 and, scraper 36 to berotated in a clockwise direction. The operating relay on the hydraulicadjusting device can also be coupled with an electric circuit fordriving the wiping cylinder 1 and the printing machine, in such a waythat when the wiping cylinder stops rotating, an automatic control forthe piston 43 intervenes to lift off the scraper 36 and, when the wipingcylinder 1 is again rotated scraper 36 is moved to engage the peripheryposition. In this way when the wiping cylinder 1 is stopped, scraper 36,is prevented from exerting a pressure and penetrating into the materialfrom which the wiping cylinder 1 is made.

A flexible scraper 47 fixed to a support 46, and made, for example, ofpolyetrafluorethylene (TEFLON registered Trademark), is in contact withthe periphery of the wiping cylinder 1 emerging from the receptacle 3 soas to remove the film ofliquid on the periphery ofthe cylinder.

In the above described embodiment, the first scraper 36 enablespractically the total mount of ink to be lifted from the surface of thewiping cylinder 1, this volume of ink being thus peeled off in largeshavings and quickly falling to the bottom of the receptacle 3. Theother rubber scrapers 33 to 35, as well as brush 32 which follows them,then ensure a final cleaning of the wiping cylinder to remove theresidue of ink. After the removal of the liquid film by scraper 47, asprinkling of water on the surface of the wiping cylinder 1 may beprovided, whereafter the film of water can be removed by anotherscraper, or by a felt wiper. Jets may be used to dampen the wipingcylinder 1 above receptacle 3 with the new cleaning solution, in whichcase it is not necessary that the wiping cylinder 1 is immersed in abath of liquid contained in the receptacle 3.

When the first scraper 36 is disposed before the damping zone, the inkremoved by this scraper can be collected in a reservoir, this practiceincreasing the economy for monochrome printing where the ink is notmixed with several colours.

Modifications can be made to the above described embodiment. Forexample, the choice of the number and of the angular positions of thescrapers and brushes can be varied. Also the use of a brush can beomitted and the work carried out only with scrapers.

The succession of supports for scrapers and brushes on the shafts, asimple mounting of the said shafts and, similarly, the simple fixationof the operating arms by means of spiral springs on guide rails 4,enables an easy exchange of the scrapers and brushes and permits,according to these. the replacement ofa scraper by a brush and viceversa.

What is claimed is:

1. In a printing apparatus having a rotatable wiping cylinder and areceptacle for cleaning fluid, the receptacle being arranged to receivea portion of the periphery of the wiping cylinder, an improvement whichcomprises a scraper mounted for movement between a first position forengaging the periphery of the wiping cylinder and a second position inwhich it is spaced from the periphery of the wiping cylinder, aplurality of secondary scrapers arranged downstream of the main scraperin the direction of rotation of the wiping cylinder, the secondaryscrapers being spaced from each other and engaging the periphery of thewiping cylinder, means being provided whereby the pressure with whicheach of said secondary scrapers engages the periphery of the wipingcylinder is adjustable by altering the angular position of each scraperwith respect to the periphery of the wiping cylinder, and wherein asupport assembly is provided for the secondary scrapers, the supportassembly including a plurality ofsupport members on which the respectivesecondary scrapers are mounted, a plurality of support shafts connectedone each to said support members, a plurality of operating armsconnected one each to the support shafts and being mounted in thereceptacle, an elongated arcuate rail arranged co-axially with thewiping cylinder and having each said operating arm resiliently coupledthereto, means mounting the rail for slidable movement in an arcuatepath substantially co-axial with the wiping cylinder, for adjusting thepressure with which the secondary scrapers engage the periphery of thewiping cylinder.

2. A printing apparatus as claimed in claim 1 in which two said supportassemblies are provided one adjacent each side surface of the wipingcylinder, and including an operating shaft connected between said twosupport assemblies for controlling said sliding movement of the rails.

3. A printing apparatus as claimed in claim 2, further comprising apinion mounted on said operating shaft, and in which gear teeth areprovided on each rail for co-operating with said pinion mounted on theoperating shaft.

4. Aprinting apparatus as claimed in claim 1, further comprising aplurality of spiral springs interconnected between said respectiveoperating arms of the support assembly and said elongated rail, thesprings being arranged generally in the lengthwise direction of therail.

5. A printing apparatus as claimed in claim 1, wherein support platesare provided having semicircular grooves open in the direction facingthe periphery of the wiping cylinder, the support shafts being supportedin said grooves of said support plates.

6. A printing apparatus as claimed in claim 1, in which means areprovided for inter-changeably mounting a brushholder and a scrapersupport downstream of the secondary scrapers in the direction of thewiping cylinder.

7. A printing apparatus as claimed in claim 1, wherein a flexiblescraper engages the periphery of the wiping cylinder downstream of thesecondary scrapers in the direction of rotation of the wiping cylinder.

8. In a printing apparatus having a rotatable wiping cylinder and areceptacle for cleaning fluid, the receptacle being arranged to receivea portion of the periphery of the wiping cylinder, an improvement whichcomprises a scraper, means for mounting said scraper for movementbetween a first position for engaging the periphery of the wipingcylinder and a second position in which it is spaced from the peripheryof the wiping cylinder, a plurality of interchangeable secondary scrapermeans and brush means arranged downstream of the main scraper in thedirection of rotation of the wiping cylinder, the secondary scrapermeans and brush means being spaced from each other and engaging theperiphery of the wiping cylinder, means for individually supporting andmounting each of said scraper means and said brush means for pivotalmovement about respective axes spaced from one another, means forrotating said scraper means and said brush means about their respectiveaxes including a single member, means for coupling each of saidsupporting means to said single member at locations spaced from the saidrespective axes, means for mounting the said single member for slidingmovement to simultaneously pivot each said scraper means and said brushmeans about their respective axes to thereby alter the pressure exertedon said wiping cylinder by said scraper means, and means for adjustablymoving said single member.

1. In a printing apparatus having a rotatable wiping cylinder and areceptacle for cleaning fluid, the receptacle being arranged to receivea portion of the periphery of the wiping cylinder, an improvement whichcomprises a scraper mounted for movement between a first position forengaging the periphery of the wiping cylinder and a second position inwhich it is spaced from the periphery of the wiping cylinder, aplurality of secondary scrapers arranged downstream of the main scraperin the direction of rotation of the wiping cylinder, the secondaryscrapers being spaced from each other and engaging the periphery of thewiping cylinder, means being provided whereby the pressure with whicheach of said secondary scrapers engages the periphery of the wipingcylinder is adjustable by altering the angular position of each scraperwith respect to the periphery of the wiping cylinder, and wherein asupport assembly is provided for the secondary scrapers, the supportassembly including a plurality of support members on which therespective secondary scrapers are mounted, a plurality of support shaftsconnected one each to said support members, a plurality of operatingarms connected one each to the support shafts and being mounted in thereceptacle, an elongated arcuate rail arranged co-axially with thewiping cylinder and having each said operating arm resiliently coupledthereto, means mounting the rail for slidable movement in an arcuatepath substantially co-axial with the wiping cylinder, for adjusting thepressure with which the secondary scrapers engage the periphery of thewiping cylinder.
 2. A printing apparatus as claimed in claim 1, in whichtwo said support assemblies are provided one adjacent each side surfaceof the wiping cylinder, and including an operating shaft connectedBetween said two support assemblies for controlling said slidingmovement of the rails.
 3. A printing apparatus as claimed in claim 2,further comprising a pinion mounted on said operating shaft, and inwhich gear teeth are provided on each rail for co-operating with saidpinion mounted on the operating shaft.
 4. A printing apparatus asclaimed in claim 1, further comprising a plurality of spiral springsinterconnected between said respective operating arms of the supportassembly and said elongated rail, the springs being arranged generallyin the lengthwise direction of the rail.
 5. A printing apparatus asclaimed in claim 1, wherein support plates are provided havingsemicircular grooves open in the direction facing the periphery of thewiping cylinder, the support shafts being supported in said grooves ofsaid support plates.
 6. A printing apparatus as claimed in claim 1, inwhich means are provided for inter-changeably mounting a brush-holderand a scraper support downstream of the secondary scrapers in thedirection of the wiping cylinder.
 7. A printing apparatus as claimed inclaim 1, wherein a flexible scraper engages the periphery of the wipingcylinder downstream of the secondary scrapers in the direction ofrotation of the wiping cylinder.
 8. In a printing apparatus having arotatable wiping cylinder and a receptacle for cleaning fluid, thereceptacle being arranged to receive a portion of the periphery of thewiping cylinder, an improvement which comprises a scraper, means formounting said scraper for movement between a first position for engagingthe periphery of the wiping cylinder and a second position in which itis spaced from the periphery of the wiping cylinder, a plurality ofinterchangeable secondary scraper means and brush means arrangeddownstream of the main scraper in the direction of rotation of thewiping cylinder, the secondary scraper means and brush means beingspaced from each other and engaging the periphery of the wipingcylinder, means for individually supporting and mounting each of saidscraper means and said brush means for pivotal movement about respectiveaxes spaced from one another, means for rotating said scraper means andsaid brush means about their respective axes including a single member,means for coupling each of said supporting means to said single memberat locations spaced from the said respective axes, means for mountingthe said single member for sliding movement to simultaneously pivot eachsaid scraper means and said brush means about their respective axes tothereby alter the pressure exerted on said wiping cylinder by saidscraper means, and means for adjustably moving said single member.